I want to be able to switch between different list views of a
document. For example, one might want to look at a text document as
a list of characters, a list of words, a list of phonemes, a list
(tree) of syntactic clauses, a list of sentences, or a list of topic
sentences that link to paragraphs, etc. Characters just happen to be
the simplest.

This is part of designing a mode I call todl-mode (for TODo List).
TODL is a variation on LISP specially designed for cyborgs :). The
idea is that if you can switch between different list views and add
hyperlinks to elements of each view, you will have a very powerful
tool for processing information.

I think of it as being somewhere in between lisp-mode,
emacs-wiki-mode, and something like outline-mode. It should be
possible to implement a TODL variant for any kind of code (so
todl-mode is also something like font-lock-mode).